what we get is a pretty classic result: a square signal in the time domain transforms into sinc in the frequency domain.
The Fourier transform of a step function includes something called Dirac's delta function you can read more about this in the following article:

http://en.wikipedia.org/wiki/Malaysia now stop asking me where is malaysia...

Posts

158

ok i understand until line 3 but how did you get from the last term in line 3 to line 4? i wasn't taught sinc functions before.Also can you try getting the answer given for this question. i want to learn how to solve such questions since it has a probability of coming out in exam. thank you